This application is for a K08 Career Development Award investigating the novel anti-inflammatory properties of breast milk in necrotizing enterocolitis (NEC). NEC affects nearly 1 out of 10 premature infants weighing less than 1500 grams, with a mortality of up to 50%. It is characterized by intestinal barrier disruption and intestinal necrosis, multi-system organ failure and death. The specific molecular mechanisms responsible for the development of NEC remain unclear. Our laboratory has shown that activation of the bacterial lipopolysaccharide receptor, toll-like receptor 4 (TLR4) is required fo NEC development and that TLR4 activation leads to two key pathological features of NEC: NF-kB-mediated inflammatory response with associated intestinal injury and impaired mucosal healing. Breast milk is the only known protective agent against NEC, but the specific protective component and protective mechanism remain unknown. Our preliminary studies show breast milk decreases TLR4 signaling and a major factor mediating this protective effect is epidermal growth factor (EGF). The overall hypothesis is that activation of the EGF receptor ameliorates NEC by antagonizing at least two major deleterious aspects of TLR4 signaling: inflammation and impaired epithelial healing. The protection seen with EGFR activation likely involves the competitive interaction of several signal transduction pathways. Therefore, we further hypothesize that the EGF in breast milk promotes intestinal cell healing by enhancing Wnt and decreasing Notch activation. To test this hypothesis, we will use our experimental NEC model to pursue the following specific aims: 1. To determine the extent that breast milk inhibits TLR4-mediated inflammatory signaling in NEC. 2. To characterize the effects of breast milk on intestinal epithelial cell proliferation and mucosal healing. 3. To determine the mechanisms by which breast milk regulates intestinal epithelial cell differentiation via TLR4-mediated Notch activation in NEC pathogenesis. The candidate is a Neonatologist who has been working closely with her mentor for the past four years. She benefits from a well-established and successful mentor with a supportive academic environment. In addition, the candidate meets on a regular basis with her Scientific Advisory Committee, which is comprised of experts in Immunology, Cell Biology and Physiology, and her collaborator, Dr. Jennifer Grandis with expertise in EGFR signal transduction. The candidate's immediate goals are to gain increased knowledge in molecular biology, immunology and signal transduction. Her long-term career goals are to become a productive independent investigator who will significantly contribute to the field studying the pathogenesis of NEC. To achieve these goals, a structured career development plan was developed which includes: gaining knowledge through educational activities, course work, conferences, frequent mentor meetings with a gradual increase in independence and a Scientific Advisory Committee who is devoted to the candidate's success.